Control apparatus for pumps



Oct. 23, 1934. w. ERNST CONTROL APPARATUS FOR PUMPS Filed Feb. 18, 1952.wil mi 11 111m E'lllHlHl' Inventor.

Patented Oct. 23, 1934 PATEN'I OFFICE CONTROL APPARATUS FOR PUMPS WalterErnst, Mount Gilead, Ohio, assignor to The Hydraulic Press ManuiacturingCompany,

Mount Gilead, Ohio Application February 18, 1932, Serial No. 593,906

3 Claims.

This invention relates to control apparatus for pumps and moreparticularly to mechanism for controlling the direction and rate ofdischarge of reversible variable discharge pumps.

Pumps of this general description are ofvarious constructions, and,generally stated, the present invention relates to control mechanismadapted for use in connection with a number of different types ofvariable discharge pumps. For the purposes of illustration oneembodiment of the in; vention will be disclosed in connection with apump of the radial, reversible, variable discharge kind now well knownin the art. Pumps of this kind are exemplified by the pump disclosed inUnited States Letters Patent 1,250,170, granted to Hele-Shaw et aL,December 18, 1917. Briefly stated, such pumps include assembliescomprising a plurality of radially arranged cylinders and pistons, therate and direction "of discharge eifected by which depend upon thecocentricity of the cylinder and piston assembly.

relative to-a drive shaft. The cylinders are usually carried by afloating ring or the like, which, by means of a cross head or othercontrol ele- 5' ment, may be shifted to vary the eccentricity of thecylinders and thereby to effect control of the pump discharge. Variousother kinds of variable discharge pumps are known in the art, and itwillbe understood that the present inven-.- .tion relates tocontrolmechanism for use in connection with pumps differing in some respectsfrom the pump illustrated herein.

An object of the invention is to improve generally the construction andoperation of control mechanism for pumps of this general character.

Another objectis to provide, in such a control mechanism, means forlimiting the maximum discharge pressure of the pump to any desiredvalue. A, further object of the invention is to 0 provide a pump controlapparatus including a piston connected to the pump flow control elementfor'shifting the latter to control the direction of flow through thepump, and means mounted independently of the pump and remote therefromfor controlling the application of pressure on said-@piston. Otherobjects will become apparent from a reading of the followingdescription, the appended claims, and the several views of the drawing,in which:

Figure 1 is a view partly in front elevation and partly in verticalsection of a pump and control mechanism embodying the invention, ahydraulic motor and circuit to which the pump is connected being shownsomewhat diagrammatically; and

Figure 2 is a fragmentary top plan view of the pump shown in Figure 1,parts being shown in section.

A practical embodiment of the invention is illustrated in theaccompanying drawing as being connected to a pump A of the radial,reversible,

variable discharge type, the pump being connected in hydraulic circuitwith a hydraulic motor or press B.

As shown, the pump A includes a casing 1, a shaft 2 which may be drivenfrom any suitable source of power, and combined intake and dischargepipes 3 and 4. The pipe 3 is connected to .the upper or pressingcylinder 5 of the press B and the pipe 4 is connected to the lower orpush back cylinders 6 thereof. When the pump is discharging through thepipe 3, the ram 7 of the press will be moved downwardly to perform apressing or other like operation, the pump at this time receiving itsintake principally from the cylinders 6. When the pump is reversed so asto discharge in the opposite direction, that is, through the pipe 4,fluid will be drawn from the cylinder 5 and delivered under pressure tothe cylinders 6 to move the push back rams 8 and ram 7 to their upperpositions. A compensating The pump A includes a pair of floating rings1313 mounted in the casing 1, theserings comprising part of a piston andcylinder assembly which is movable radially with respect to the pumpshaft for varying the pump discharge.

Rods 14-14 are connected to the rings 13-13 and extend through thecasing at 1515, the outer ends of the, rods being connected by a crosshead or pump flow control element 16 secured to the rods by nuts 17-17.Rods 1818, also connected to the rings 13-13, extend through theopposite side of the casing at 1919, the outer ends of these rods beingconnected by a cross head 20 secured to the rods by nuts 21.

Referring now to the control apparatus form-- ing the subject matter ofthe present invention, a bracket 22 is mounted on one side of the pumpcasing and serves to support a control cylinder '23.thereon. A doubleacting pump control pis-- the pump discharge or to reverse the directionof discharge.

For moving the piston 24 to shift the cross head 16 so as to vary orreverse the discharge of the pump, means are provided for applying fluidpressure to either side of the piston. In the lot embodiment shown, thispressure-applying means-includes a low pressure auxiliary pump 26arranged to receive fluid from the tank 11 through the medium of asuction pipe 27, and to discharge fluid under relatively low pressurethrough a pipe 28 to,a pilot valve generally designated 29 carried by abracket 30 secured to the press 13, the pilot valve serving to. controlthe application of pressure on the respective sides of the piston 24through pipes 31 and 32. A relief valve 33, which may be of aconventional pressure responsive type, is interposed between the pipe 28and the tank 11 to permit by-passing of the low pressure fluid to thetank when fluid isnot being delivered through either of the pipes 31 or32.

The pilot valve includes a casing 34, a liner 35 mounted inthe casingand defining a valve chamber 36, and a piston valve generally designated37. The liner. 35 is provided with ports 38 adjacent its upper end whichregister with an annular chamber 39 formed in the valve casing 34, witha passage 40' at the central part of the liner registering with anannular chamber 41 in the valve casing, and with ports 42 adjacent thelower end of the liner and registering with an annular chamber 43 formedin the valve casing.

The piston valve 3'7 includes. a pair "of spaced heads 44 and 45connected by an intervening reduced portion 46 and a'stem 47 whichextends downwardly from the head 45 through the lower end of thevalvecasing, leakage around thestem being prevented by a packing 48 heldin place by a gland nut 49. The piston valve is formed with an internalpassage 49a which provides communication between the valve chamber atthe opposite ends of the piston valve and serves to maintain, equal unitpressures in the opposite ends of the chamber to facilitate shifting ofthe valve. A pipe 49?) provides constant communication between the upperend of the valve casing and the tank 11 for a purpose to be describedlater.

The heads 44 and 45 are so spaced that, when the head 44 is disposed tocover the ports 38, the head 45 will cover the ports 42. There issufficient clearance between the valve heads and the inside of the linerto permit a slight leakage through the ports 38 and 42 when the valveheads cover the ports for a purpose to be explained later.

A spring 50 surrounding the valve stem 47 and interposed between thegland nut 49 and a washer 51 secured to'the lower end of the stem servesto urge the piston valve 3'? downwardly from the position shown inFigure 1. For moving the valve upwardly, I have'provided a ram-operatedrod 52-which is maintained in alignment with the valve stem 4'? by meansof a bracket 53 secured'to the press base and a boss 54-at the end of anarm 55 connected'to the press platen 56, the rod 52 being arranged forfree sliding movement within the bracket 53 and the boss 54. A collar 57secured to the rod 52 is adapted to be engaged by the boss 54 when therams move upwardly so as to lift the rod 52 to bring the upper endof thelatter into engagement with the stem 4'7 and to raise the piston valve37. In' order to raise the piston valve upwardly from its Figure 1position when the parts are at rest, .1 have provided a treadle 58pivotally supported on. a

bracket 59- and having a rounded head 60 disposed for engagement withthe lower end of the rod 52.

In operation, assuming that the par s are in the positions shown inFigure 1 and that the pumps A and 26 are running, there will be nomovement of the press parts until the piston valve 37 has been shifted,since the floating rings 13 of the pump A are in neutral position andthe pump is not discharging. Fluid discharged by the pump 26 will beby-passed through the relief valve 33 to the tank 11. In order toinitiate a downward movement of the press rams, the treadle 58 will bedepressed so as to lift the rod 52 and the valve 37. Fluid delivered bythe auxiliary pump will now flow through the pipe 28, the annularchamber 41, the passage 40, the valve chamber 36, the ports 38', thepassage 39, and the pipe 32 to the inner end of the control cylinder 23on the pump. The fluid entering the inner end of the control cylinderwill act upon the piston 24 and move the latter and the floating rings13 toward the left so as to causethe pump A to discharge through thepipe 3 into the pressing cylinder 5 and to drive the ram 7 downwardly.'During movementof the piston 24 to the left, fluid contained in theouter end of the cylinder 23 will be discharged therefrom through thepipe 31, the annular chamber 43 in the pilot valve casing, the ports 42,the passage 49a in the piston valve 3'7, the upper end of the pilotvalve chamber, and the pipe 491). When the piston 24 has moved thefloating rings to the left to an extent which causes the pump A todischarge at the desired rate, the operator will release pressure on thetreadle 58 so as to permit the spring 50 to return the piston valve 37to its Figure 1 position, wherein flow of fluid from the pump 26 tothe'control cylinder 23 is arrested, and the piston 24 will bemaintained in its new position.

chamber 41 and passage 40 in the pilot valve, the

valve chamber 36, the ports 42, the annular passage 43, and the pipe 31into the outer end of the control cylinder 23. Fluid thus introducedinto the control cylinder will act upon the outer end of the piston 24to move'the latter and the floating rings 13 to the right so as toreverse the pump and cause it to discharge through the pipe 4 into thepush back cylinders 6 of the press. When the piston 24 and floatingrings of the pump have been moved to the right to an extent causing thepump to discharge through the pipe 4 at the desired rate, the operatorwill depress the treadle 58 until the rod 52 has lifted the .pistonvalve 3'7 to its Figure 1 position, wherein there will be no furtherflow of fluid from the auxiliary pump to the cylinder'23. However, if itis desired that the pump A deliver fluid through the pipe 4 atthemaximum discharge rate'during.

the upward movement of the press rams, the operator need not return thepiston valve 3'7 to its Figure 1 position, and the floating rings 13will be moved to their extreme right hand positions. .When the ramsapproach the limit of their upward travel, the boss 54 will engage thecollar 57 on the rod 52 so as to raise the latter and the piston valve3'7 against the urge of the spring 50. Therams will continue to moveupwardly until the piston valve 3'7 has been moved to a position aboveits Figure 1 position, after which fluid willbe delivered to the innerend of the control cylinder 23in the manner previously described.

This will, cause the piston 24 and the floating rings to be moved to theleft so as to cause the pump to discharge through the pipe 3 and tostart the rams moving downwardly. As soon as the rams have moveddownwardly enough to allow the spring 50 to move the piston valve .37 toa position slightly below its Figure 1 position, fluid will be deliveredto the outer end of the control cylinder 23, which, as previouslystated, will move the piston 24 and the floating rings to the right soas to cause the pump to discharge through the pipe 4. There will beseveral back and forth I movements oi the piston 24 and the floatingrings,

and corresponding movements of the press rams for a short time, untilfinally the floating rings of the pump will come to rest in a neutralposi.

the cylinder 62 and is connected to the cross head 20 by means of apiston rod 64. A pipe 65 provides communication between the pipe 63 andthe inner 'end'of the overload cylinder, and a pipe 66 providescommunication between the pipe 4 and the outer nd oi the cylinder. If,during downward movement of the press rams, pressure builds up in thepipe 3 to a predetermined point, this pressure, acting through the pipe65 and in the inner end of the overload .cylinder, will move 7 theoverload piston 63 and the cross head 20 to the right so as to reducethe rate of discharge by the'pump. During this movement of the piston 63and the cross head 20, the piston 24 will also necessarily move to theright. Fluid contained in the inner end of the control cylinder 23 will.

be forced out through the pipe 32 and will leak past the valve head 44intolthe upper endof the valve chamber, and then will flow through thepipe 491) to the tank 11. Similarly, if, during a returnmovement oi thepress rams while the pump is discharging through the pipe 4, pressureshould build up beyond a predetermined amount, this pressure, actingthrough the pipe 66- and in the outer end of the overload cylinder 62,will force the piston 63 and the cross head to the left to move thefloating rings toward their neutral posi tion and to reduce the rate ordischarge of the pump. 'During this movement of the piston 63 totheleftthe piston 24 also must be moved to the lett, and the fluidcontained in the left hand end of the cylinder 23 will be dischargedthrough the pipe 31 and will leak past the valve head 45 into the lowerend-oi the valve chamber, after which it will flow through theinternalpassage 49a in the piston valve, the pipe 49b, and thence to the tank11.

From the foregoing it will be apparent that my improved controlapparatus is extremely simple in that the piston 24 isconnected'directly to the -shiitable flow control elements of the pump;and

' there are no mechanical connections between the pump and the hydraulicmotor served by the pump. The movable element 3'7 of the pilot valve isfree from mechanical connection with the flow control element otthepump, so that the pilot valve may be mounted conveniently on the press,and the pump may belocated at some distance from the press, as is oftendesirable.- The control apparatus disclosed herein may be'used inconnection with various specific kinds-.01 pumpsother than thatillustrated, and it will be understood that various changes may be madein the speciflc construction and relative arrangement of .the partswithout departing from the spirit of the invention as defined in theclaims.

I claim:

1. In combination a reversible pump of the type provided with ashiftable piston and cylinder assembly for controlling the direction-oiflow of fluid through the pump; a hydraulic motor having reciprocableram means; hydraulic connections between the pump and motor; a pumpcontrol cylinder; a hydraulic pump control piston mounted therein andconnected to said piston and cylinder assembly; means for supplyingfluid une der pressure to said control cylinder including a pilot valvemounted on said hydraulic motor independently of said pump and having amovable element free from mechanical connection with said piston andcylinder assembly, an auxiliary pump Iorsupplying fluid under pressureto said pilot valve, and a hydraulic connection between said pilot valveand said control cylinder; means for biasing the movable element of saidpilot valve in one direction and ram operated means for automaticallyshifting the movable element of said pilot valve in the oppositedirection.

. 2. In combination, a reversible variable discharge pump of the typeincluding a shiftable flow control element; a hydraulic motor havingreciprocable double acting ram means; hydraulic circuit connectionsbetween the opposite sides of said pump and the opposite sides of saidram -means respectively; a hydraulic overload cylinder; a double actingoverloadpist'on mounted therein and connected to said flow controlelement; hydraulic connections between the opposite ends of saidoverload cylinder and said hydraulic circuit connections respectively; apump control cylinder; a hydraulic pump control piston mounted thereinand connect'ed'to said flow control element; means for supplying fluidto said control cylinder including a pilot valve mounted on saidhydraulic motor independently of said pump and having a movable elementfree from mechanical connection with the flow control element of saidpump, and a hydraulic connection between said pilot valve andsaidcontrol cylinder; means for biasing the movable element or saidpilot valve in one direction and ram operated means ior automaticallyshifting the movable element 01. said pilot valve in the opposite direc-3. In combination a reversible pump oi. the type provided with ashiitable flow control element a hydraulic motor having reciprocable rammeans; hydraulic connections between the pump and motor; a pump controlcylinder; a hydraulic pump control piston mounted therein and connectedto said flow control element; means for supplying fluid under pressureto said control cylinder including a pilot valve mounted on said hy-'draulic motor independently of said pump and 14 pilot valve andsaidcontrol cylinder; 'means forbiasing the movable element of said pilotvaive in one direction; and ram operated means for shifting the movableelement of said valve in the opposite direction.

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